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Commit d51468f

Browse files
Add delete-node-in-a-bst solution
1 parent 1b060af commit d51468f

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3 files changed

+106
-11
lines changed

3 files changed

+106
-11
lines changed
Lines changed: 42 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,42 @@
1+
<?php
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declare(strict_types=1);
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namespace leetcode;
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use leetcode\util\TreeNode;
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class DeleteNodeInABinarySearchTree
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{
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public static function deleteNode(?TreeNode $root, int $key): ?TreeNode
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{
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if (!$root) {
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return $root;
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}
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if ($root->val > $key) {
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$root->left = self::deleteNode($root->left, $key);
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} elseif ($root->val < $key) {
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$root->right = self::deleteNode($root->right, $key);
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} else {
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if (!$root->left) {
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return $root->right ?? new TreeNode();
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}
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if (!$root->right) {
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return $root->left ?? new TreeNode();
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}
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$node = self::findMinNode($root->right);
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$root->val = $node->val;
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$root->right = self::deleteNode($root->right, $node->val);
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}
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return $root;
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}
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private static function findMinNode(?TreeNode $node): TreeNode
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{
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while (!$node) {
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$node = $node->left;
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}
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return $node;
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}
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}

β€Žsrc/leetcode/util/TreeNode.phpβ€Ž

Lines changed: 13 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -30,22 +30,24 @@ public static function dfsTreeValues(TreeNode $tree, array &$list): void
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3131
public static function bfsTreeValues(TreeNode $tree): array
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{
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$result = $queue = [];
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$queue[] = $tree;
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$ans = $items = $queue = [];
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$queue = [$tree];
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while ($queue) {
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/** @var TreeNode $current */
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$current = array_pop($queue);
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$result[] = $current->val;
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if ($current->right) {
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$queue[] = $current->right;
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}
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/** @var TreeNode $node */
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$node = array_shift($queue);
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if ($node instanceof TreeNode) {
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array_push($ans, $node->val ?: null);
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if ($node->left) {
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array_push($queue, $node->left);
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}
4243

43-
if ($current->left) {
44-
$queue[] = $current->left;
44+
if ($node->right) {
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array_push($queue, $node->right);
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}
4547
}
4648
}
4749

48-
return $result;
50+
return $ans;
4951
}
5052

5153
public static function fromArray(array $array): ?TreeNode
Lines changed: 51 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,51 @@
1+
<?php
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declare(strict_types=1);
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namespace leetcode\tests;
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use leetcode\DeleteNodeInABinarySearchTree;
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use PHPUnit\Framework\TestCase;
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use leetcode\util\TreeNode;
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class DeleteNodeInABinarySearchTreeTest extends TestCase
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{
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private TreeNode $p;
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private TreeNode $q;
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private ?TreeNode $t;
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protected function setUp(): void
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{
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$this->p = new TreeNode(5);
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$this->p->left = new TreeNode(3);
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$this->p->right = new TreeNode(6);
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$this->p->left->left = new TreeNode(2);
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$this->p->left->right = new TreeNode(4);
24+
$this->p->right->left = new TreeNode();
25+
$this->p->right->right = new TreeNode(7);
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27+
$this->q = new TreeNode(5);
28+
$this->q->left = new TreeNode(3);
29+
$this->q->right = new TreeNode(6);
30+
$this->q->left->left = new TreeNode(2);
31+
$this->q->left->right = new TreeNode(4);
32+
$this->q->right->left = new TreeNode();
33+
$this->q->right->right = new TreeNode(7);
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35+
$this->t = null;
36+
}
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public function testDeleteNode(): void
39+
{
40+
$node1 = DeleteNodeInABinarySearchTree::deleteNode($this->p, 3);
41+
self::assertSame([5, 4, 6, 2, null, null, 7], TreeNode::bfsTreeValues($node1));
42+
43+
$node2 = DeleteNodeInABinarySearchTree::deleteNode($this->q, 0);
44+
self::assertSame([5, 3, 6, 2, 4, null, 7], TreeNode::bfsTreeValues($node2));
45+
46+
$node3 = DeleteNodeInABinarySearchTree::deleteNode($this->t, 0);
47+
if (!$node3 instanceof TreeNode) {
48+
self::assertSame([], (array) $node3);
49+
}
50+
}
51+
}

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